U.S. Pat. No. 5,135,804 describes a 1-step compaction process for making a film, such as for a sail, from polyethylene fibres. The examples use a range of pressures, of from 4.6 MPa to 46 MPa. The process is exclusively for application to gel spun fibres having a weight average molecular weight of at least about 500,000, preferably at least about a million and more preferably between about 2 million and about six million.
It would be desirable to use a compaction process employing a low pressure, for example in an autoclave, for melt spun fibres but none is available. There are compaction processes for melt spun fibres, but they are 2-step processes, employing high compaction pressures.